
Scoria!
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Updated 1 month ago
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. It is typically dark in color (brown, black or purplish-red), and basaltic or andesitic in composition. Scoria has relatively low density, as it is riddled with macroscopic ellipsoidal vesicles (gas bubbles), but in contrast to pumice, scoria always has a specific gravity greater than 1 and sinks in water.
Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta (lapilli, blocks, and bombs), for instance in Strombolian eruptions that form steep-sided scoria cones, also called cinder cones. Scoria's holes or vesicles form when gases dissolved in the original magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Most scoria is composed of glassy fragments and may contain phenocrysts. A sample from Yemen was mainly composed of volcanic glass with a few zeolites (e.g., clinoptilolite).
The geological term cinder is synonymous and interchangeable with scoria, though scoria is preferred in scientific literature. The word comes from Greek σκωρία, skōria, rust. In earlier terminology, scoria was usually defined with a size range, e.g. 2 to 24 mm (0.079 to 0.945 in) in diameter, but neither color nor composition was typically a part of the definition.[5][6] During the 1980s, the size range disappeared from the definition, and a requirement was added that scoria be black or reddish in color and/or mafic in composition.
- https://en.wikipedia.org/wiki/Scoria
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Big Daddy!
RyanzRocksScoria is a type of volcanic rock that forms from the rapid cooling of lava rich in gas. Here's a detailed explanation: Formation: Scoria is typically formed during volcanic eruptions when dissolved gases in the magma come out of solution as the pressure decreases, creating bubbles in the lava. When this gas-charged lava is ejected and cools quickly, it solidifies with these bubbles trapped inside, resulting in a porous texture. Characteristics: Texture: Scoria has a vesicular texture, meaning it is full of small cavities or vesicles, which are the remnants of gas bubbles. These vesicles can give scoria a lightweight, pumice-like appearance, though scoria is generally denser than pumice. Color: It is usually dark in color, ranging from black to dark brown or reddish-brown, due to its high iron and magnesium content. Composition: Scoria is primarily basaltic or andesitic in composition, containing minerals like plagioclase, pyroxene, and olivine. Uses: Scoria is used in construction for lightweight concrete,39 views -
Lava Spud!
RyanzRocksThis is a type of vesicular basalt. Vesicular basalt is a type of basalt that has many small cavities or vesicles, which form when gas bubbles are trapped in the lava as it cools and solidifies. The texture with numerous small holes is characteristic of this type of rock.36 views -
Lava Spud Cut!
RyanzRocksScoria is a highly vesicular, dark-colored volcanic rock that forms from the rapid cooling of gas-rich lava, typically basaltic in composition. Here's a more detailed explanation: Formation: Scoria forms when lava with high gas content is ejected from a volcano. As the lava is propelled into the air, the gas bubbles within it expand rapidly due to the decrease in pressure, creating a frothy texture. When this frothy lava cools and solidifies quickly, it traps these bubbles, resulting in a rock full of cavities or vesicles. Characteristics: Texture: Scoria has a rough, porous texture due to the numerous vesicles or gas bubbles trapped within it. These vesicles can make up to 50% of the rock's volume. Color: It is typically dark in color, ranging from black to dark brown or red, due to its basaltic composition. However, oxidation can sometimes give it a reddish hue. Density: Despite being a rock, scoria is relatively lightweight because of its high porosity. Uses: Scoria is used in various applications: Construction: Due to its lightweight nature, it's used in lightweight concrete, as drainage material, and in landscaping. Abrasive: Its rough texture makes it useful as an abrasive material. Gardening: It can improve soil drainage in gardening.31 views -
Lava Spud!
RyanzRocksThe rock in the image appears to be a type of volcanic rock known as #scoria. Scoria is characterized by its numerous macroscopic ellipsoidal vesicles, which are holes or cavities within the rock formed by the escape of gas during the cooling of lava. Here's a brief overview: Type: Volcanic Rock (Igneous) Composition: Basaltic, sometimes andesitic Texture: Vesicular (full of small cavities) Color: Typically dark, ranging from black to deep red or brown Formation: Rapid cooling of basaltic lava, trapping gas bubbles Uses: Sometimes used in construction, as lightweight aggregate, or in landscaping The vesicles in scoria are a result of trapped gases that couldn't escape during the rapid cooling of lava, which is typical for volcanic eruptions. If you find this rock interesting, examining it with a magnifying glass or under a microscope could reveal even more about its structure and possibly its origins. If you're into geology or rock collecting, scoria makes for a fascinating example of how geological processes can create such distinctive textures.22 views